Surveillance Works for Small Renal Tumors

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Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

Note that this retrospective study of registry data suggested that surveillance of renal masses <2 inches (4 cm) was associated with better outcomes than surgery.

Be aware that, given the nonrandomized nature of the study, it is unclear whether these results are due to unmeasured confounding.

ORLANDO -- Surveillance for small kidney tumors led to survival and other outcomes at least as good as those associated with surgery, according to a retrospective study involving 8,300 older patients.

During a median follow-up of 5 years, patients in surveillance had a 16% lower risk of death from any cause compared with surgically managed patients. From 6 months on, patients in surveillance had a significantly lower risk of death from any cause, a difference that reached 63% among patients followed for more than 3 years, reported William C. Huang, MD, of New York University.

Kidney cancer-specific mortality was 3% overall and did not differ significantly between patients in surveillance and those who were surgically managed. Surgery significantly increased the odds of cardiovascular events, Huang said during a press briefing prior to the Genitourinary Cancers Symposium.

"Surveillance is a reasonable option for patients with small kidney tumors who are older or have considerable comorbid conditions," he said. "A number of small kidney tumors can become lethal over time; therefore, surgery remains the treatment of choice for patients with a normal life expectancy."

A rising incidence of kidney cancer has turned the disease into one of the 10 most common malignancies in the U.S. The increase is thought to reflect expanded use of imaging techniques, as most of the tumors are discovered incidentally. About two thirds of new tumors are <2 inches and constitute a heterogeneous group of tumors that has a variable malignant potential, said Huang.

Historically, surgery has been standard of care for small renal masses, but recent studies have suggested that surgery might not be necessary for older or morbidly ill patients. Some of the evidence has suggested that surgery might predispose poorer-risk patients to worse non-oncologic outcomes.

To examine current trends and outcomes in the management of small renal tumors, Huang and colleagues searched the NCI Surveillance, Epidemiology, and End Results (SEER) database, linked to Medicare claims data. They limited the search to patients 66 and older with newly diagnosed tumors during 2000 to 2007. They further limited the search to renal tumors <2 inches.

The principal outcomes of interest were overall survival, cancer-specific survival, and cardiovascular events.

Investigators defined surveillance by the absence of a claim for surgery during the first 6 months after diagnosis. The SEER data showed that the rate of surveillance for small kidney tumors increased from 25% in 2000 to 37% in 2007. Overall, however, 78% of patients underwent surgery.

Patients in surveillance had a significantly lower risk of death from any cause compared with the surgery group (HR 0.84, 95% CI 0.75 to 0.94). Surgery was associated with a trend toward better survival during the first 6 months. From 7 to 36 months, the trend turned in favor of surveillance, which was associated with a 30% lower all-cause mortality.

The mortality difference between groups continued to widen with increasing follow-up beyond 36 months.

Consistent with previous evidence of a possible adverse effect of surgery on non-oncologic outcomes, surveillance was associated with a 50% reduction in the hazard for cardiovascular events as compared with surgically managed patients (HR 0.51, 95% CI 0.44-0.60, P<0.00001). The cardiovascular risk was most pronounced in patients who underwent radical nephrectomy, said Huang.

"It is important to show that one does not have a negative impact of increase in kidney cancer mortality by watching these lesions," said press briefing moderator Bruce Roth, MD, of Washington University in St. Louis. "Others have advocated biopsying these lesions to improve the algorithm.

"This study shows that not intervening not only won't have a negative impact but it may be a negative impact to do surgery on these individuals because they will have an increase in cardiovascular events and maybe cardiovascular mortality."

The Genitourinary Cancers Symposium is co-sponsored by the American Society of Clinical Oncology, the American Society for Radiation Oncology, and the Society of Urologic Oncology.

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